Phosphorization of α-FeO Boosts Active Hydrogen Mediated Electrochemical Nitrate Reduction to Ammonia.

Inexpensive iron-based materials are considered promising electrocatalysts for nitrate (NO ) reduction, but their catalytic activity and spontaneous corrosion remain challenges. Here, the α-FeO active surface is reconstructed by gradient phosphorization to obtain FeP with higher electrochemical activity. FeP optimizes the adsorption energy of NO and its reduction intermediates, meanwhile promote the generation of active hydrogen (H) but inhibit its generation of H. More importantly, Fe and P can serve as binding sites for NO and H, respectively, which improves the electron utilization of NO deoxygenation and the efficiency of the subsequent hydrogenation for the selective synthesis of NH. 91.7% NO conversion rate is achieved for the reduction of 100 mL 200 mg L NO -N, 99.3% ammonia (NH selectivity (yield of 1.79 mg h cm), and 91.4% Faraday efficiency in 3 h. The high-purity solid NHCl is finally extracted by gas extraction and vacuum distillation (81.4% recovery). This study provides new insights and strategies for the conversion of NO to NH products over iron-based electrocatalysts.